Documento original del Skill
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Hedera Token Service (HTS) System Contract
HTS precompile at 0x167 enables Solidity contracts to create and manage Hedera-native tokens with built-in compliance controls (KYC, freeze, pause) and custom fees.
Quick Reference
Imports:
solidity
import {HederaTokenService} from "@hashgraph/smart-contracts/contracts/system-contracts/hedera-token-service/HederaTokenService.sol";
import {KeyHelper} from "@hashgraph/smart-contracts/contracts/system-contracts/hedera-token-service/KeyHelper.sol";
import {ExpiryHelper} from "@hashgraph/smart-contracts/contracts/system-contracts/hedera-token-service/ExpiryHelper.sol";
import {HederaResponseCodes} from "@hashgraph/smart-contracts/contracts/system-contracts/hedera-token-service/HederaResponseCodes.sol";Safe variants (auto-revert on failure): SafeHTS.sol, SafeViewHTS.sol
Critical: HBAR Payment Required
Token creation requires explicit HBAR value payment (not just gas):
solidity
// ❌ WRONG - fails with INSUFFICIENT_TX_FEE
(int rc, address token) = createNonFungibleToken(token);
// ✅ CORRECT
(int rc, address token) = createNonFungibleToken{value: msg.value}(token);Call from TypeScript:
typescript
await contract.createToken(name, symbol, {
gasLimit: 350_000,
value: ethers.parseEther("15"), // ~$1-2 USD of HBAR
});Token Key System
Seven key types control token operations (bit positions for keyType field):
| Key | Bit | Value | Controls |
|---|---|---|---|
| ADMIN | 0 | 1 | Update token, keys, deletion |
| KYC | 1 | 2 | Grant/revoke KYC |
| FREEZE | 2 | 4 | Freeze/unfreeze accounts |
| WIPE | 3 | 8 | Wipe balances |
| SUPPLY | 4 | 16 | Mint/burn |
| FEE | 5 | 32 | Update fees |
| PAUSE | 6 | 64 | Pause all operations |
Use KeyHelper for key construction:
solidity
keys[0] = getSingleKey(KeyType.SUPPLY, KeyValueType.CONTRACT_ID, address(this));See references/keys.md for key value types and JSON tuple format.
Association Model
Accounts must associate with tokens before receiving them:
solidity
int rc = associateToken(accountAddress, tokenAddress);
require(
rc == HederaResponseCodes.SUCCESS ||
rc == HederaResponseCodes.TOKEN_ALREADY_ASSOCIATED_TO_ACCOUNT,
"Association failed"
);Common Patterns
Fungible Token Creation
solidity
function createToken() external payable {
IHederaTokenService.HederaToken memory token;
token.name = "My Token";
token.symbol = "MTK";
token.treasury = address(this);
token.expiry = createAutoRenewExpiry(address(this), 7776000); // 90 days
(int rc, address created) = createFungibleToken{value: msg.value}(
token, 1000000, 18 // initialSupply, decimals
);
require(rc == HederaResponseCodes.SUCCESS, "Create failed");
}Mintable NFT Collection
solidity
function createNFT() external payable {
IHederaTokenService.HederaToken memory token;
token.name = "My NFT";
token.symbol = "MNFT";
token.treasury = address(this);
token.tokenSupplyType = true; // FINITE
token.maxSupply = 10000;
IHederaTokenService.TokenKey[] memory keys = new IHederaTokenService.TokenKey[](1);
keys[0] = getSingleKey(KeyType.SUPPLY, KeyValueType.CONTRACT_ID, address(this));
token.tokenKeys = keys;
token.expiry = createAutoRenewExpiry(address(this), 7776000);
(int rc, address created) = createNonFungibleToken{value: msg.value}(token);
require(rc == HederaResponseCodes.SUCCESS, "Create failed");
}
function mintNFT(bytes memory metadata) external {
bytes[] memory metas = new bytes[](1);
metas[0] = metadata;
(int rc, , int64[] memory serials) = mintToken(tokenAddress, 0, metas);
require(rc == HederaResponseCodes.SUCCESS, "Mint failed");
}KYC-Enabled Token
Treasury must self-grant KYC after creation:
solidity
// After token creation with KYC key
int kycRc = grantTokenKyc(tokenAddress, address(this));
require(kycRc == HederaResponseCodes.SUCCESS, "Self-KYC failed");Response Code Handling
Always check response codes. SUCCESS = 22.
solidity
require(responseCode == HederaResponseCodes.SUCCESS, "Operation failed");Common codes: See references/response-codes.md
Additional References
- API Reference: references/api.md - All function signatures
- Custom Fees: references/fees.md - Fixed, fractional, royalty fees
- Compliance Controls: references/compliance.md - KYC, freeze, pause details
- Struct Definitions: references/structs.md - HederaToken, Expiry, etc.
- Troubleshooting: references/troubleshooting.md - Common errors and fixes
